The following three possibilities can occur when the system time cannot be changed:
1, motherboard battery (CMOS) no electricity,
2, there is a virus (such virus modification time is to make anti-virus software can not be used, or cause some software operation is not normal, such as securities stock stock software),
3, you do not have the right to modify the time.
First, how to determine whether the CMOS battery is not electricity.
Boot into the BIOS, modify the time, save the exit, turn off the computer restart, and then into the CMOS view, if the time is in accordance with the modified after the operation, the battery OK. Otherwise need to replace the battery, if the replacement of good batteries or not, it may be the motherboard problem.
Second, how to judge is a virus.
(Because of Vista users, you need to turn off UAC to use the proofing controls on this site.) So here's the time to start mentioning the change, all by hand set the time method)
Some computers can be modified under Windows, but they quickly jump to a wrong time, which is a virus.
If time can be modified, but the time after reboot is not correct. Then you can change the time, start the computer, into the BIOS, if this time is wrong, that is the motherboard battery is dead, if this time is right, into Windows after the time is wrong, that is the virus.
If the time can not be changed, such as the site's right time control can not play a role, it may be a virus may also have no permissions. Therefore, you need to determine whether you are currently logged on users have the right to modify the time.
Third, check time Modify permissions:
First find out your Windows username, if you do not know, press Ctrl+alt+del three keys to view.
1. Click Start--> Run input secpol.msc, point OK. (or "control Panel → admin tools → local Security Policy")
2. The Management dialog box for the local security policy is followed by the--> Local policy--> User rights Assignment in the left tree box.
3. Locate and double-click Change system time in the list on the right to pop up a window.
(If the operation cannot be completed, you do not have administrative authority, log in with the administrator again)
A list of privileged users is listed, and if you find your username, you don't have permission.
If you already have your username, it means you have permission, but if the time is still not modified, it is a virus.
Well, if it belongs to a situation that does not have permissions, then increase the permissions and then modify the time. If the judge is a virus, and currently there is no effective anti-virus method, it is recommended to cancel all user time to modify permissions, and then look back in this article!
Cancel permissions: Select users from the list, click Delete, and then click OK
Additional permissions: Click "Add User or group", then click Advanced, select the user from the list, confirm the selection, and then click OK to close.
Cancel User: Click the check box for the Cancel local policy setting, and then OK.
Additional permissions: Click Add (A) ... button, pop up a window, select the user to add permissions from the list, double-click or click the Add button, and then make sure to close and then OK.
Reboot the computer. You need to reboot your computer, either by canceling permissions or by adding permissions.
If you have canceled all user modification permissions, at the time of startup, enter the BIOS manual setup time. If you start Windows again, the virus cannot modify the time. Future antivirus clean, then the time to modify the permissions plus.
If the original did not have permission to increase the permissions after the time is still unable to adjust, indicating that there is a virus, it can still revoke the permissions and then lock the time. If you have problems with computer hardware and software, please visit the Rain Forest Wind Exchange forum, where there are professional engineers to solve your problem together.